This invention relates to a process for agglomerating at least two particulate food products, in which the particles of at least one secondary product are made to adhere to the particles of a main product by means of a liquid agglomerating agent.
The invention also relates to an apparatus for continuously carrying out this process, comprising an inclined rotary drum, a frame supporting the drum, drive means for rotating the drum about its axis, means for introducing the main product at the upper end of the drum and means for removing the agglomerated product at the lower end of the drum.
The problem of incorporating heat-sensitive components, such as certain proteins or certain amino acids, flavourings or vitamins, in cereal flakes obtained, for example, by roller drying or by extrusion of a cereal-based paste has been solved in various ways, including dry-mixing or agglomeration of the particles of the heat-sensitive components with the cereal flakes after drying of the flakes.
Now, the dry mixing of particulate products which often differ considerably in their granulometry and apparent density is difficult and involves the danger of overrapid separation. This risk is particularly serious when a product of relatively low bulk density is dry-mixed with a product of relatively high bulk density.
However, the known agglomeration processes intended to overcome this drawback of dry-mixing can also have certain disadvantages, particularly when the particulate products differ in their hygroscopicity.
Thus, one known process comprises moistening an intimate mixture of flakes based on starch issuing from a roller dryer and powder-form food or aromatic products with water in a fluidized bed or an agglomeration channel to make the powder adhere to the flakes. This process involves the risk of agglomerating the powder particles with one another when they are more hygroscopic than the flakes.
Similarly, another known process comprises introducing cereal flakes and a sugar syrup into a rotary drum, allowing the flakes and the syrup to mix along the first two thirds of their path in the drum and then introducing an aromatic powder of the freeze-dried ice cream type into the last third of the drum so that it adheres to the still tacky flakes. This process involves the risk of agglomerating the flakes with one another and of obtaining an irregular distribution of the powder around the flakes.